#include <stdio.h>
#include <math.h>

int main()
{
    double x;
    scanf("%lf", &x);

    double sin_value = 0.0;
    double term = x;
    int n = 1;
    
    while (fabs(term) >= 1e-8) {
        sin_value += term;
        n += 2;
        term = -term * x * x / (n * (n - 1));
    }

    printf("%.6lf\n", sin_value);

    return 0;
}